I think it does, but these dictionary phases are saying otherwise
– DuckAug 10 '18 at 20:49

I think it might acually be if they the writer belives in having more than one life
– DuckAug 10 '18 at 20:50

you are talking about singular vs plural, not countable vs uncountable. and most of the discrepancy seems to revolve around singular they and/or whether to use a singular or plural noun when the subject is actually plural
– Arm the good guys in AmericaAug 10 '18 at 21:17

It should be life. Someone is singular. their is used as singular they.
– JimAug 10 '18 at 21:58

Going back, that the problem came up when you wanted to make (some) corrections… isn’t promising, I’m sorry to say. Corrections to “… one’s” paper will work in almost no circumstances; to “… someone’s” paper would work but still, how could it help? Will you really not distinguish between “someone” and “people” being successful in “their” lives? If you can’t face “someone” being successful in “his” or “her” or even “his/her” life, why not use “someone being successful in life”? Broadly, is it easier to change the language, or our usage of it?
– Robbie GoodwinNov 3 '18 at 20:47

Thanks for your answer, but all the example sentences are from dictionary.
– hahaAug 11 '18 at 6:26

@haha I don't understand. You wanted an explanation for when one word is used over the other, which is what I was providing. The fact that they are from a dictionary doesn't mean that the usage is understandable. If it were, you wouldn't have been confused. :) Also—the one example I flagged as incorrect, I still believe to be incorrect. It doesn't matter if it was from a dictionary or not; they are not infallible.
– Jason BassfordAug 11 '18 at 8:49

I agree with every other word you posted but how can you justify "The way each person lives their own life", please?
– Robbie GoodwinAug 17 '18 at 19:23

@RobbieGoodwin I know that some people don't like it, but it's the singular, gender-neutral third-person pronoun. It's been accepted by both The Chicago Manual of Style and the Associated Press Style Book, and is quickly gaining common use.
– Jason BassfordAug 18 '18 at 2:40

Since I can't be bothered to squeeze this into 27 Comments, could you first explain how your “When” could change whether you should use countable or uncountable Life?

Further, what did you mean by “corrections to one’s paper”? Whose paper? Which paper? Why? How could that be relevant, please?

“When someone is successful in their lives…” will always be unjustifiable.

“When someone is successful in their life…” will always be questionable, but many people will insist it is acceptable.

“When someone is successful in his or her life…” will always be acceptable.

“When someone is successful in life…” will always be acceptable.

“To give someone more control over their own life…” is basically wrong, twice. It should be “To give people more control over their own lives” or to “To give someone more control over his or her own life”. Does that much make sense?

“The idea that women should take control over their own lives…” is luckily uncontentious, as is “shouldn’t make moral judgements about the way people live their lives.”

“The way people live their life” is simply wrong, though most commentators will happily subsume that into the context.

“Every aspects of their private life” is more wrong than “Every aspect of their private lives”… unless the subjects share the same private life. Immediate family members do; neighbours might; others prolly don't.

“Every aspect of their private lives has been laid bare” makes no difference at all.

“Millions have bought the book (for whatever reason)” is fine.

“Things that people use in their ordinary life” might as easily use “… lives”, the difference being complex and hardly relevant here.

“They sacrificed their personal goals for their family life” might be fine, or horrible. Depending on what you specifically meant, please consider “He/She/They sacrificed personal goals for family life…”.